Dataset Information

Physiologic blood flow is turbulent.

ABSTRACT: Contemporary paradigm of peripheral and intracranial vascular hemodynamics considers physiologic blood flow to be laminar. Transition to turbulence is considered as a driving factor for numerous diseases such as atherosclerosis, stenosis and aneurysm. Recently, turbulent flow patterns were detected in intracranial aneurysm at Reynolds number below 400 both in vitro and in silico. Blood flow is multiharmonic with considerable frequency spectra and its transition to turbulence cannot be characterized by the current transition theory of monoharmonic pulsatile flow. Thus, we decided to explore the origins of such long-standing assumption of physiologic blood flow laminarity. Here, we hypothesize that the inherited dynamics of blood flow in main arteries dictate the existence of turbulence in physiologic conditions. To illustrate our hypothesis, we have used methods and tools from chaos theory, hydrodynamic stability theory and fluid dynamics to explore the existence of turbulence in physiologic blood flow. Our investigation shows that blood flow, both as described by the Navier-Stokes equation and in vivo, exhibits three major characteristics of turbulence. Womersley's exact solution of the Navier-Stokes equation has been used with the flow waveforms from HaeMod database, to offer reproducible evidence for our findings, as well as evidence from Doppler ultrasound measurements from healthy volunteers who are some of the authors. We evidently show that physiologic blood flow is: (1) sensitive to initial conditions, (2) in global hydrodynamic instability and (3) undergoes kinetic energy cascade of non-Kolmogorov type. We propose a novel modification of the theory of vascular hemodynamics that calls for rethinking the hemodynamic-biologic links that govern physiologic and pathologic processes.

SUBMITTER: Saqr KM

PROVIDER: S-EPMC7512016 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Physiologic blood flow is turbulent.

Saqr Khalid M KM Tupin Simon S Rashad Sherif S Endo Toshiki T Niizuma Kuniyasu K Tominaga Teiji T Ohta Makoto M

Scientific reports 20200923 1

Contemporary paradigm of peripheral and intracranial vascular hemodynamics considers physiologic blood flow to be laminar. Transition to turbulence is considered as a driving factor for numerous diseases such as atherosclerosis, stenosis and aneurysm. Recently, turbulent flow patterns were detected in intracranial aneurysm at Reynolds number below 400 both in vitro and in silico. Blood flow is multiharmonic with considerable frequency spectra and its transition to turbulence cannot be characteri ...[more]

PMID: 32968087

Similar Datasets

Project description:Cardiac disease and clinical intervention may both lead to an increased risk for thrombosis events due to a modified blood flow in the heart, and thereby a change in the mechanical stimuli of blood cells passing through the chambers of the heart. Specifically, the degree of platelet activation is influenced by the level and type of mechanical stresses in the blood flow. In this article we analyze the blood flow in the left ventricle of the heart through a computational model constructed from patient-specific data. The blood flow in the ventricle is modelled by the Navier-Stokes equations, and the flow through the mitral valve by a parameterized model which represents the projected opening of the valve. A finite element method is used to solve the equations, from which a simulation of the velocity and pressure of the blood flow is constructed. The intraventricular blood flow is complex, in particular in diastole when the inflow jet from the atrium breaks down into turbulent flow on a range of scales. A triple decomposition of the velocity gradient tensor is then used to distinguish between rigid body rotational flow, irrotational straining flow, and shear flow. The triple decomposition enables the separation of three fundamentally different flow structures, that each generates a distinct type of mechanical stimulus on the blood cells in the flow. We compare the results in a simulation where a mitral valve clip intervention is modelled, which leads to a significant modification of the intraventricular flow. Further, we perform a sensitivity study of the results with respect to the positioning of the clip. It was found that the shear in the simulation cases treated with clips increased more compared to the untreated case than the rotation and strain did. A decrease in valve opening area of 64% in one of the cases led to a 90% increase in rotation and strain, but a 150% increase in shear. The computational analysis opens up for improvements in models of shear-induced platelet activation, by offering an algorithm to distinguish shear from other modalities in intraventricular blood flow.

Project description:Hematogenous metastasis accounts for the majority of cancer-related deaths, yet the mechanism remains unclear. Circulating tumor cells (CTCs) in blood may employ different pathways to cross blood endothelial barrier and establish a metastatic niche. Several studies provide evidence that prostate cancer (PCa) cell tethering and rolling on microvascular endothelium via E-selectin/E-selectin ligand interactions under shear flow theoretically promote extravasation and contribute to the development of metastases. However, it is unknown if CTCs from PCa patients interact with E-selectin expressed on endothelium, initiating a route for tumor metastases. Here we report that CTCs derived from PCa patients showed interactions with E-selectin and E-selectin expressing endothelial cells. To examine E-selectin-mediated interactions of PCa cell lines and CTCs derived from metastatic PCa patients, we used fluorescently-labeled anti-prostate specific membrane antigen (PSMA) monoclonal antibody J591-488 which is internalized following cell-surface binding. We employed a microscale flow device consisting of E-selectin-coated microtubes and human umbilical vein endothelial cells (HUVECs) on parallel-plate flow chamber simulating vascular endothelium. We observed that J591-488 did not significantly alter the rolling behavior in PCa cells at shear stresses below 3 dyn/cm(2). CTCs obtained from 31 PCa patient samples showed that CTCs tether and stably interact with E-selectin and E-selectin expressing HUVECs at physiological shear stress. Interestingly, samples collected during disease progression demonstrated significantly more CTC/E-selectin interactions than samples during times of therapeutic response (p=0.016). Analysis of the expression of sialyl Lewis X (sLe(x)) in patient samples showed that a small subset comprising 1.9-18.8% of CTCs possess high sLe(x) expression. Furthermore, E-selectin-mediated interactions between prostate CTCs and HUVECs were diminished in the presence of anti-E-selectin neutralizing antibody. CTC-Endothelial interactions provide a novel insight into potential adhesive mechanisms of prostate CTCs as a means to initiate metastasis.

Project description:Vascular endothelial and hematopoietic cells hold a close relationship that is initiated during development, but that continuously broadens to include new functions aimed at maintaining homeostasis in the adult organism. Here, we report on a population of aortic intimal resident macrophages (MacAIRs) that is a permanent feature of the inner vessel wall (tunica intima) of the aorta in regions of turbulent flow and that shares the luminal surface with the endothelium. MacAIRs were found to be transcriptionally distinct from other macrophages and closely associated with the endothelium in the absence of pathology. Lineage tracing analysis indicated that adult MacAIRs were derived from definitive hematopoietic lineage precursors that migrated from the ductus arteriosus seeding the aorta immediately post-birth in areas of turbulent flow including the lesser curvature of the aortic arch and branch openings. These aortic resident macrophages expanded via direct cell renewal and continued to grow in aged aortae to also populate regions of laminar flow. Binding of MacAIRs relied heavily on expression of endothelial ICAM that interacts with CD11c on macrophages. Genetic deletion of CD11c significantly impaired anchorage of MacAIRs to the endothelium. To clarify the biological significance of this population of macrophages, we used a dual diphtheria toxin induced-depletion system that efficiently eliminated MacAIRs in adult mice. Utilizing this model, we found that absence of MacAIRs led to progressive fibrin accumulation and formation of microclots that, once dislodged, can cause blockade of vessels and organ failure. In fact, 40% of the animals with genetic-mediated depletion of MacAIRs died within 2 weeks post-depletion suggesting that these macrophages were required to clear fibrin deposits in regions of turbulent blood flow. These findings advance our knowledge of how vascular endothelial cells profit from this unique interaction with macrophages to control hemostasis, prevent intravascular clotting, and ensure vascular health.

Dataset Information

Physiologic blood flow is turbulent.

Publications

Physiologic blood flow is turbulent.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets